Daisuke Shibuya

Coffee consumption and the risk of primary liver cancer: Pooled analysis of two prospective studies in Japan

Although case‐control studies suggested that coffee consumption is associated with a decreased risk of liver cancer, no prospective cohort study has been carried out. To examine the association between coffee consumption and the risk of liver cancer, we conducted a pooled analysis of data available from 2 cohort studies in Japan. A self‐administered questionnaire about the frequency of coffee consumption and other health habits was distributed to 22,404 subjects (10,588 men and 11,816 women) in Cohort 1 and 38,703 subjects (18,869 men and 19,834 women) in Cohort 2, aged 40 years or more, with no previous history of cancer. We identified 70 and 47 cases of liver cancer among the subjects in Cohort 1 (9 years of follow‐up with 170,640 person‐years) and Cohort 2 (7 years of follow‐up with 284,948 person‐years), respectively. We used Cox proportional hazards regression analysis to estimate the relative risk (RR) and 95% confidence interval (CI) of liver cancer incidence. After adjustment for potential confounders, the pooled RR (95% CI) of drinking coffee never, occasionally and 1 or more cups/day were 1.00 (Reference), 0.71 (0.46–1.09) and 0.58 (0.36–0.96), respectively (p for trend = 0.024). In the subgroup of subjects with a history of liver disease, we found a significant inverse association between coffee consumption and the risk of liver cancer. Our findings support the hypothesis that coffee consumption decreases the risk of liver cancer. Further studies to investigate the role of coffee in prevention of liver cancer among the high‐risk population are needed.

The increase of female breast cancer incidence in Japan: Emergence of birth cohort effect

During recent decades, breast cancer incidence has been increasing in Japan. According to the latest reports from several cancer registries in Japan, the breast has become the leading cancer site in female cancer incidence. To analyze the trend of breast cancer incidence in detail, we summarized female breast cancer incidence in Miyagi Prefecture, Japan during 1959–1997, and evaluated the period and cohort effect on breast cancer incidence using the age‐period‐cohort model. Age‐specific and age‐standardized rates have increased over successive calendar periods. Around 1980, an accelerated increase in these incidence rates took place. A full model including age, period and cohort was best fitted to the trend of incidence. In the model, the effects of period and cohort were statistically significant. The nonlinear effect for cohort indicates an increasing trend, beginning with the cohort in 1888–1897, and the nonlinear effect for period showed a clear increase in risk with calendar period. Furthermore, the full model including a linear component showed a steadily upward trend in the cohort effect. Based on our own epidemiologic studies previously conducted in Miyagi Prefecture, and other published reports, the cohort effect is likely to be related to the change in prevalence of women with risk factors such as low parity and insufficient breastfeeding. We believe that the emergence of the cohort effect is an important finding, although the period effect may also persist. The significant cohort effect may give a caution for continuous increase of breast cancer incidence in Japan.

Cigarette smoking and the risk of gastric cancer: a pooled analysis of two prospective studies in Japan.

To examine the association between cigarette smoking and the risk of gastric cancer, we conducted a pooled analysis of 2 population‐based prospective cohort studies in rural northern Japan. Cohort 1 included 9,980 men (≥40 years old) and Cohort 2 included 19,412 men (40–64 years old). The subjects completed a self‐administered questionnaire on cigarette smoking and other health habits. We identified 228 cases of gastric cancer among Cohort 1 subjects (9 years of follow‐up with 74,073 person‐years) and 223 among Cohort 2 subjects (7 years of follow‐up with 141,675 person‐years). From each cohort, we computed the relative risk (RR) and 95% confidence interval (CI) of gastric cancer associated with smoking using a Cox regression analysis and pooled these estimates to obtain summary measures. The pooled multivariate RRs (95% CIs) for current smokers and past smokers compared to subjects who had never smoked were 1.84 (1.39–2.43) and 1.77 (1.29–2.43), respectively. The higher number of cigarettes smoked per day among current smokers was associated with a linear increase in risk (trend p < 0.05). The significant increase in risk for past smokers remained for up to 14 years after cessation. An increased risk was noted for cancer of the antrum but not for cardia or body lesions. The risk was increased for both differentiated and nondifferentiated histologic subtypes. Our findings support the hypothesis that cigarette smoking is a risk factor for gastric cancer.

Fruit and vegetable consumption and risk of colorectal cancer in Japan: The Miyagi Cohort Study

OBJECTIVE Adequate fruit and vegetable intake has been suggested to protect against colorectal cancer. However, several recent prospective studies have reported no association. We therefore examined the association between fruit and vegetable intakes and the risk of colorectal cancer in a prospective cohort study in Japan. DESIGN Between June and August 1990, 47 605 Japanese men and women completed a self-administered questionnaire, including a food-frequency questionnaire. We divided the subjects into quartiles based on their self-reported fruit and vegetable consumption. There were 165 colon cancer and 110 rectal cancer incidences identified during 7 years of follow-up, to the end of December 1997. We used Cox proportional hazards models to estimate the relative risk (RR) of developing colorectal cancer according to the level of fruit and vegetable consumption, applying adjustments for potential confounders. RESULTS No statistically significant association was observed between fruit and vegetable consumption and the risk of colorectal cancer. The multivariate RR of colon cancer in the highest quartile of fruit and vegetable intake compared with the lowest was 1.13 (95% confidence interval (CI) 0.73-1.75), the RR for vegetables alone was 1.24 (95% CI 0.79-1.95) and that for fruit alone was 1.45 (95% CI 0.85-2.47). The corresponding multivariate RRs for rectal cancer were 1.12 (95% CI 0.67-1.89), 1.14 (95% CI 0.67-1.93) and 1.41 (95% CI 0.73-2.73). CONCLUSIONS We found no association between the consumption of fruit and vegetables and the risk of colorectal cancer among the Japanese population.

Age-specific interval breast cancers in Japan: estimation of the proper sensitivity of screening using a population-based cancer registry.

The age‐specific sensitivity of a screening program was investigated using a population‐based cancer registry as a source of false‐negative cancer cases. A population‐based screening program for breast cancer was run using either clinical breast examinations (CBE) alone or mammography combined with CBE in the Miyagi Prefecture from 1997 to 2002. Interval cancers were newly identified by linking the screening records to the population‐based cancer registry to estimate the number of false‐negative cases of screening program. Among 112 071 women screened by mammography combined with CBE, the number of detected cancers, false‐negative cases and the sensitivity were 289, 22 and 92.9%, respectively, based on the reports from participating municipalities. The number of newly found false‐negative cases and corrected sensitivity when using the registry were 34 and 83.8%, respectively. In detected cancers, the sensitivity of screening by mammography combined with CBE in women ranging from 40 to 49 years of age based on a population‐based cancer registry was much lower than that in women 50–59 and 60–69 years of age (40–49: 18, 71.4%, 50–59: 19, 85.8%, 60–69: 19, 87.2%). These data suggest that the accurate outcome of an evaluation of breast cancer screening must include the use of a population‐based cancer registry for detecting false‐negative cases. Screening by mammography combined with CBE may therefore not be sufficiently sensitive for women ranging from 40 to 49 years of age. (Cancer Sci 2008; 99: 2264–2267)

Alcohol consumption and the risk of cancer in Japanese men: the Miyagi cohort study

The objective of this study was to investigate the association between alcohol consumption and the risk of total cancer, and to estimate the proportion of total cancer attributable to drinking habit in Japanese men. From June through August 1990, a total of 21 201 Japanese men completed a self-administered questionnaire on various health habits, including alcohol consumption. During 153 389 person-years of follow-up through December 1997, we identified a total of 882 cases of cancer. We used Cox proportional hazards regression to estimate the relative risk of total cancer according to categories of alcohol consumption. The risk for total cancer was significantly higher in ex-drinkers than never-drinkers. There was a dose–response relationship between the amount of alcohol consumed and the risk of total cancer among current drinkers: multivariate RRs in reference to never-drinkers (95% confidence intervals (CI)) were 1.1 (0.8–1.3), 1.3 (1.0–1.7), and 1.3 (1.1–1.7) in current drinkers who consumed less than 22.8 g, 22.8–45.5 g, 45.6 g or more alcohol per day, respectively (P for trend <0.001). Estimated 17.9% (95% CI 3.1–30.5) of total cancer risk was attributable to drinking habit. In our findings, approximately 20% of the total cancer cases in Japanese men may be prevented by alcohol control.

Time spent walking and risk of colorectal cancer in Japan: the Miyagi Cohort study.

Higher levels of physical activity have been consistently associated with a lower risk of colon cancer in earlier epidemiological studies. The specific benefits of walking, however, remain relatively unexplored. In 1990, 20 519 men and 21 469 women in Japan completed a self-administered questionnaire including a question on time spent walking per day. During 7 years of follow-up, 260 cases of colorectal cancer were documented in 305 790 person-years. We used the Cox proportional hazards regression model to estimate the relative risk of incident cancer (colorectal, colon, and rectal) according to three levels of walking. Time spent walking was inversely associated with risk of colorectal cancer incidence in men. Compared with men who walked 0.5 h or less per day, the multivariate relative risks were 1.06 (95% confidence interval 0.72–1.57) for men who walked between 0.5 and 1 h per day, and 0.57 (95% confidence interval 0.38–0.83) for men who walked 1 h or more per day (P for trend=0.003). Time spent walking per day was associated with a lower risk of colon cancer in Japanese men but not in women, and there was no association between time spent walking and the risk of rectal cancer.

Personality and cancer survival: the Miyagi cohort study.

We tested the hypothesis that personality plays a role in cancer outcome in a population-based prospective cohort study in Japan. In July 1990, 41 442 residents of Japan completed a short form of the Eysenck Personality Questionnaire-Revised and a questionnaire on various health habits, and between January 1993 and December 1997, 890 incident cases of cancer were identified among them. These 890 cases were followed up until March 2001, and a total of 356 deaths from all causes was identified among them. Cox proportional-hazards regression was used to estimate the hazard ratio (HR) of death according to four score levels on each of four personality subscales (extraversion, neuroticism, psychoticism, and lie), with adjustment for potential confounding factors. Multivariable HRs of deaths from all causes for individuals in the highest score level on each personality subscale compared with those at the lowest level were 1.0 for extraversion (95% CI=0.8–1.4; Trend P=0.73), 1.1 for neuroticism (0.8–1.6; Trend P=0.24), 1.2 for psychoticism (0.9–1.6; Trend P=0.29), and 1.0 for lie (0.7–1.5; Trend P=0.90). The data obtained in this population-based prospective cohort study in Japan do not support the hypothesis that personality is associated with cancer survival.